Higher serum levels of 25-hydroxyvitamin D (25(OH)D) correlated with a reduced risk of cancer in women. This study aimed to determine what serum levels of vitamin D conferred a reduced risk of developing cancer.1

In 1980, initial research suggested a relationship between vitamin D deficiency and the development of some colon cancers. Researchers had observed that populations at higher latitudes with less sunlight experienced greater rates of 25(OH)D deficiency and greater rates of colon cancer. Subsequent studies showed correlations with 25(OH)D deficiency and increased risk of other cancers, including breast, lung, and bladder.

This study, published in PLoS One, used 25(OH)D levels in the blood to measure vitamin D. Researchers pooled data from 2 previous studies for their analyses. One study was a randomized clinical trial of 1169 women (Lappe study), and the other was a prospective cohort study of 1135 women (GrassrootsHealth prospective cohort).

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Researchers found the median blood serum level of 25(OH)D in the Lappe study was was 30 ng/mL. The median blood serum level of 25(OH)D in the Grossroots Health prospective cohort was 48 ng/mL. The age-adjusted cancer incidence was 1020 per 100 000 person-years in the Lappe study and 722 per 100 000 person-years in the GrassrootsHealth prospective cohort.

As 25(OH)D serum levels increased, cancer incidence decreased. Women with serum levels of 25(OH)D greater than 40 ng/mL experienced a 67% reduced risk of cancer than women with serum levels of 25(OH)D of 20 ng/mL or less.

“We have quantitated the ability of adequate amounts of vitamin D to prevent all types of invasive cancer combined, which had been terra incognita until publication of this paper,” said Cedric Garland, DrPH, adjunct professor at the University of California (UC) San Diego School of Medicine, Department of Family Medicine and Public Health and member of Moores Cancer Center at UC San Diego Health, and co-author of the study.

“These findings support an inverse association between 25(OH)D and risk of cancer and highlight the importance for cancer prevention of achieving a vitamin D blood serum concentration above 20 ng/mL, the concentration recommended by the IOM for bone health.”


1. McDonnell SL, Baggerly C, French CB, et al. Serum 25-hydroxyvitamin D concentrations ≥40 ng/ml are associated with >65% lower cancer risk: pooled analysis of randomized trial and prospective cohort study [published online ahead of print April 6, 2016]. PLoS One. doi:10.1371/journal.pone.0152441.